The practice of chiropractic revolves around the basic tenet that various ailments can be relieved through manipulation of the patient's bone structure, particularly through manipulation of the spine and the vertebrae making up the spine. If the vertebrae are out of position spinal nerves can be pinched and considerable pain can result. The chiropractor, through his manipulations, attempts to relieve the pain by attempting to move the vertebrae to a more comfortable position. Unfortunately, it is often difficult for a patient to maintain the posture necessary to achieve relief, especially since such posture often requires a differential loading on the spine. For patients who have a sedentary occupation, such as vehicle operators or office workers, differential loading, by way of manipulation of the pelvis, is difficult to achieve since, when sitting on a soft cushion or chair seat, the weight of the patient is essentially evenly distributed over the buttocks.
In order to maintain differential loading when in a seated position the patient should have his hips at different elevations, with the unaffected side being raised relative to the affected side so as to remove pressure from the affected side. Prior to the present invention such differential loading of the spine through placing the hips (the ilia) at different elevations could only be achieved by placing a hard object such as a book or a piece of wood between the seat cushion and the patient so as to raise the unaffected side relative to the affected side. Such practice is very unsatisfactory as there is no adjustment possible except by changing the thickness of the insert placed between the seat cushion and the patient. It is also very difficult under such circumstances for the chiropractor to suggest the correct thickness of insert since the insert probably would be used in conjunction with seats of different degrees of softness and there would be no guarantee that the same degree of relief would be provided to the patient with each seat that he sits upon.